1. Field of the Invention
The present invention relates to a method of recycling an image supporting material on which images can be formed from an image supporting material which comprises (a) a non-absorbent substrate that absorbs no liquids and (b) an absorbent swelling layer that can absorb liquids and swells when absorbing liquids, which is overlaid on the non-absorbent substrate and on which images are formed, by eliminating from the image supporting material an image-forming material which constitutes the images which are formed by image formation apparatus such as copying machines, facsimile apparatus or printers. The present invention also relates to an apparatus for performing the above-mentioned method.
2. Discussion of Background
With the recent spread of printers and copying machines which employ various kinds of image formation processes such as electrophotography, thermal image transfer method, ink-jet printing method using a hot-melt ink, and other printing methods, an extremely large quantity of paper has been consumed. Papers used as the image supporting materials are generally made of wood pulp. The consumption of a large quantity of paper has caused the problems of environmental disruption of the earth due to deforestation. Furthermore, a large quantity of image supporting materials which bear images thereon formed by the above-mentioned image formation methods is discarded, so that the refuse disposal has become a serious problem.
A transparent sheet used as an image supporting material for an overhead projector (OHP) (hereinafter referred to as the OHP sheet) comprises as a base material a plastic film which is generally made of a polyester film or an acetate film. Raw materials for such plastics films are generally synthesized from fossil materials such as petroleum or produced from wood in the same manner as in the manufacturing of paper. Therefore, also with respect to the OHP sheets, a large quantity consumption thereof is not desirable in view of the protection of petroleum resources and global environmental conservation. When the OHP sheets are shredded by a shredder, the wearing of blades used in the shredder is considerable. When image supporting materials such as papers, and the OHP sheets are mixed and shredded, the recycling of the image supporting materials becomes almost impossible. Therefore conventionally the OHP sheets are often discarded without being shredded, which may cause a problem in the protection of secret image information recorded on the OHP sheets.
Conventionally, in order to solve the above problems, used papers or films are collected and beaten or melted again to recycle such image supporting materials. However, such a recycling method has the shortcoming that the efficiency of energy consumption thereof is so low that it occurs that recycled materials are more expensive, but poorer in quality than brand-new materials produced using new raw materials.
In order to solve this problem, Japanese Laid-Open Patent Application 4-300395 discloses a method of removing toner images from a toner-image bearing support material, that is, a toner-image bearing copy paper, by spraying or applying a solvent which is used in a copying machine for dissolving toner therein, and then removing the toner images from the toner-image bearing support material, using a cleaning blade or the like.
Many other methods of dissolving or swelling an image forming material to remove the image forming material from an image supporting material, which is similar to the above-mentioned methods, have already been proposed. In order to dissolve or swell the image forming material, an organic solvent such as toluene, xylene or tetrahydrofuran is usually employed. However, in view of safety, it is not desirable to use such organic solvents in a place where a special ventilator or solvent recovery apparatus is not provided.
Japanese Laid-Open Patent Application 1-29729 discloses a method of peeling images away from an image supporting material which comprises a non-absorbent material which absorb substantially no liquids, such as plastics, metal, a paper into which liquids hardly penetrate, or ceramics, by superimposing a thermofusible releasing member on the image supporting material with the application of heat thereto.
Japanese Laid-Open Patent Application 2-55195 discloses an image supporting material comprising a PET film which is subjected to a surface releasing treatment by coating the surface with a silicone seal agent.
Japanese Laid-Open Patent Application 4-64472 discloses an apparatus for peeling images away from the above-mentioned image supporting material subjected to the surface releasing treatment.
The above-mentioned method and apparatus are advantageous over other conventional methods and apparatus in that no liquids are employed for removing image forming materials from the image supporting material.
The image supporting material employed in the above-mentioned method, however, significantly differs from paper which is in general use as an image supporting support material, for example, in terms of glossiness, surface properties and thickness, and gives a feeling of physical disorder to the users when actually used. Furthermore, this image supporting material includes the laminated releasing film which is expensive, and therefore the cost thereof is high. Furthermore, the image fixing performance of this image supporting material is not good, so that there is the problem that images are peeled off the image supporting material when touched with fingers or clothes, resulting in staining the fingers or clothes.
In order to solve the problems of the image fixing performance and the safety of the above-mentioned image supporting material, Japanese Laid-Open Patent Applications 6-222604 and 7-311523 disclose a method using an image supporting material comprising a non-absorbent substrate which absorbs no liquids and a swelling layer overlaid thereon, which swells with the absorption of liquids. Even with respect to images formed on a recycled image supporting material obtained from this image supporting material, the image fixing performance thereof can be appropriately maintained. When an image forming material which constitutes the images formed on the image supporting material is removed therefrom, a liquid which can swell the above-mentioned swelling layer is applied to the swelling layer so as to cause the swelling layer to swell, reducing the adhesion between the images and the image supporting material, whereby the removal of the images from the image supporting material is significantly facilitated. Furthermore, a liquid comprising water as the main component can be used as the above-mentioned liquid which can swell the swelling layer. Therefore, this method is also excellent in terms of safety. The image supporting material comprising (a) the non-absorbent substrate which absorbs no liquids, and (b) the swelling layer which is overlaid thereon and swells by the absorption of the liquid, hardly deteriorates due to the use of the non-absorbent substrate and therefore can be used repeatedly. In addition, this image supporting material has an advantage that the image forming material can be removed by use of a relatively small amount of the above-mentioned liquid.
From the image supporting material disclosed in Japanese Laid-Open Patent Applications 6-222604 and 7-311523, the image forming material which constitutes images formed thereon can be removed, for instance, (a) by immersing the image-bearing image supporting material in a liquid which swells the swelling layer, and vibrated in the liquid, (b) by applying ultrasonic waves to the image-bearing image supporting material, or (c) by rubbing the images off the image supporting material with a soft material such as sponge or felt. The image forming material can be easily removed from the image supporting material by any of the above-mentioned methods. However, the liquid in which the image supporting material is immersed is contaminated with the removed image forming material, so that some removing means for removing the image forming material from the liquid is required. As such removing means, a filter may be employed. However the filter is easily clogged with a relatively small amount of the image forming material. Therefore it is in practice difficult to eliminate the image forming material from the liquid by using the above-mentioned removing means.
Furthermore, there are many cases where the image forming material contains a dye which is soluble in the liquid. In such cases, if the dye is dissolved in the liquid, it is extremely difficult to make the liquid clear by removing the dissolved dye therefrom, using the filter only. It is time consuming to remove the image forming material from the liquid by a conventional apparatus and accordingly it is extremely difficult to remove the image forming material from the liquid at high speed.
As mentioned above, in the method disclosed in Japanese Laid-Open Patent Application 7-311523, the image supporting material which comprises a non-absorbent substrate which absorbs no liquids and a swelling layer which absorbs liquids and swells is employed. It is considered that in order to remove images from the supporting material, if the image forming material which constitutes the images is heated to the softening point of the image forming material, and is then transferred to a peeling member, there will be no problems as in the case where the image forming material is removed from the liquid. However, varieties of image supporting materials are used for commercially available varieties of image formation apparatus. Accordingly, varieties of image forming materials are used, which exhibit largely different physical properties with different melted and adhesion states, so that the above-mentioned method is not always applicable to all the image forming materials for the removal thereof at high speed. Furthermore, it is extremely difficult to remove the image forming material from a large solid image area formed on the image supporting material.
In Japanese Laid-Open Patent Application 8-44260, the applicants of the present invention proposed a recycling method and a recycling apparatus, in which a liquid is applied to an image supporting material comprising (a) a non-absorbent substrate that absorbs no liquids and (b) an absorbent swelling layer that can absorb liquids and swells with absorption of liquids, which is overlaid on the non-absorbent substrate and on which images are formed, and at least part of the swelling layer is covered with a seal member through which water does not permeate, thereby substantially preventing the evaporation of water from the swelling layer, and the swelling layer is subjected to heat treatment, whereby an image forming material which constitutes the images is peeled away from the image supporting material.
However, preferable conditions for employing the above-mentioned recycling method and recycling apparatus are limited in that it is preferable that the amount of the liquid applied to the image supporting material be controlled so as not to exceed a predetermined amount in order to prevent the reduction of the rigidity of the image supporting material.